Fluid-pressure system



Sept. 21 1926.

B. s. AlKMAN FLUID PRESSURE SYSTEM Filed March 8, 1924 3 Sheets-Sl'xeel'I l Sept. 21 1926.

B. S. AIKMAN FLUID PRESSURE SYSTEM Filed March 8, 1924 3 Sheets-Sheet 2 l as @165655651 l M l t Sept. 21 1926.

B. S. AIKMAN FLUID PRESSURE SYSTEM Filed March 8, 1924 3 Sheets-Sheet 5 {Mil/76.556,5:

.u le

- ervoir have served satisfactorily. c

air pressure carried in the reservoiris from -pagina sept. 21,1926.

d UNITED- STATESl I/ :sun'roir s. Arnim, or

mmw um, w'raooilsnr, Assienon. or cin-iur.: ro :on A. mann., or omesso, immers.

Application lied Karak l, 19,4. Serial .im I

tems.

The modern garge provides a source of compressed air for in ments for such service ave heretofore been such that a single stage compressor'and res- The usual 7 0 to 100 pounds.

With the advent of large truck tires reuiring air at from 100 to 150 pounds, the limits of satisfactory single stage compression have been reached, and it is generally considered necessary to employ atwo stage compressor for this service.

Since the average garage isnow equipped for 90 pounds, such raising of the pressure entails a considerable expense inthe cost of. a new compressor and a suitable motor, and in many cases a heavier tank.

I have observed that in the usual gara 'or service station only a small percent of t e air is employed for high pressure requirements, but the entire amount that is used for all purposes must be thus compressed against the high pressure of the receiving tank.

In thus compressing against this high false head for the major amount of air, a ye considerable Vwaste of power is entail The cost of compressing air increases veil;r

rapidly as the terminal pressure isinerease 'provide a system in which the air is compressed to the lower pressure and stored in the reservoir at the lower pressure which is suitable for pum ing up the majority of tires, and the air or pumping up truck tires and the like is further com ressed by an air operated booster which delivers air at a'd'esired higher pressure. Thus the air that is stored is kept at a low pressure. This means, first, that t e cost of compressing is low and mechanical efficiency is igh; second, that the loss from leakage is less; and finally it means that so much of the equipment which is now standard need not be changed.' The booster operates only as there is a demand for air, and hence no more air than is required forimmediate operation is compressed to the higher pressure. This eiects a saving in initial investment and it saves in cost of operating the system.

I have provided a novel form of booster which takes air from thereceiving tank and compresses a part of the same as required and delivers vit at a higher pressure.

My invention relates toiiuid pressure sys-l tires. The require` lerating a system according to my invention,

In pneumatic apparatus it is often di'icul to get the working cyhnder filled with the iiuid. In the present case I insure a full charge pf air in the compressing cylinders by causing them to function as motor cylinder s prior to their operation as compressor cyhn ers. Furthermore,I rovide means forem loying a smglehose ordi nsing eitherigh or low ressure when e same is desired. Obvious y, two separate distributing systems ma employed if desired. f,

le I have described my invention in connection with an air pump system for inflating tires, it isobvious that t e invention has many other uses.

' The boosting ratio is'determined by the ratios of piston areas. This may be widely variedvas' desired. Also the booster of my invention. may be employed to boost by two stage action instead of single stage action, as will be described more in detail later.

In order to acquaint those skilled in the art with the manner of construction and op- I shall now describe a tire iniiating system embodying the invention. i

- Fig. 1 is a diagram of a system embodying my invention;

' Fig. 2 is a front elevational view of a switching valve for employing a single hose connection which may be switched to the reservoir or to the booster to give either low pressure or high pressure, respectively;

Fig. 34 is a cross section through the valve shown in Fig. 2 in a plane parallel tothe plane of the paper;

Fig. 4 is -a longitudinal section through the booster and throughthe control valve therefor; A

Fi 5 is a diagrammatic v iew showin the application of .the valve illustrated in Fig. 2 to the system disclosed in Fig. 1; and

Fig. 6 is a detail view of an'automatic charging valve.

In Fig. 1, I have shown the compressor 1, which may be a single stage compressor,.having the air-inlet 2 and-discharge pipe 3 leadv ing to a reservoir 4, which may be of any suitable capacity and of suilicient strength to hold air under pressure at approximately 125 pounds with a suitable factor of safety.

. The compressor 41 is driven by a suitable electric motor 5 governed by `a pressure controlled governor 6 which may be of any suit- 11o lau@ for'm. while I have' shown the ,congressor- 1as -driven by-an electric motor, 1t

branches at 8 and -9, the branch 8 leading to a iexible Hose 10 having a suitable automatic charging valve 11 adapted to engage the nipple of the usual tire valve for inflating the tire.

The branch 9 leads through a suitable shut-off valve 13 to the booster 12 and from the discharge connection 14 ofthe booster 12 to a flexible hose 15 having the automatic valve 16.

The automatic valves 11 and 16 may be of the type shown in Figi 6 which .consists essentially of a casing 10 provided wit-h an opening 11 to which either the hose 10 or 15 may be secured. Positioned in another opening 12 in the casing 10 is a movable valve member 13 having a shoulder 14 for engaging the wall 15 of the casing 10. The member 13 is provided with an orifice 16 connected to aperture 17 The member 13 is also equipped with an enlarged portion c18 for preventing the member 13 from being pushed too far into the casing. Formed on the inside of the casing is a lug 19 which is connected to the end of the member 13 by a spring 20 which exerts a downward force or'pressure on the member 13. This downward pressure normally maintains the shoulder 14 of the member 13 on the portion designated by reference numeral 15, thereby closing the valve. It is, of course, obvious that the pressure of the air in the valve 'will also aid in maintaining the valve closed. By' exerting a very slight pressure on the enlarged portion 18 the valve may be easily opened permitting the air under pressure to be discharged therefrom.

The booster 12 comprises a central cylinder 20, which is litt'edwith a. double-acting piston 21. Suitable piston rings are mounted on the piston 21 to prevent leakage between the piston andthe cylinder walls. The cylinder 20 is provided with, an integral valve housing 22, having the longitudinal passageways 23 and 24 leading through passageways 25 and 26 'to the ends of the cylinder 20 upon opposite sides of the piston 21. Compressor cylinders and 31, of smaller diameter than the diameter of the motor cylinder 20, are bolted to the ends of the motor cylinder 20, and plungers or pistons 32 and 33 are secured to the iston 21 and to each other axially in line. T e piston 21, with both of its plungers 32 and 33, may be made integral ifdesired. The ends of the plungers 32 and 33 are provided with suitable packing rings of any preferred or well-known construction. The compressor cylinders 30 and 31 are provided with suit- Vable heads 84 and 35, these heads each comprising suitable automatic inlet check valves 40 and automatic discharge check valves 41. These valves are held to their seats by suitable springs, as is well known in the art. The discharge check valves 41 are connected to passageways42 in the heads 34 and 35 to -a common manifold passageway 43-44 formed in the motor cylinder walls and in the compressor cylinder walls, so that compressed'air discharged at the boosted pressure may pass to the discharge connection 14.

The valve passageways 23 and 24 terminate in ports45 and 46 in a valve seat, which is adapted to be served by the D-slide valve 47. An exhaust port 48 lies betweenv the cylinder ports 45 and 46. The D-slide valve 47 -is adapted to be shifted to connect one of the ports to exhaust and the other to live air, which live air connection leads from the pipe 9 to the interior of the valve housing 28.

The slide valve 47 is held to its seat by springs 49, and during normal operation is further held by the pressure of the air inside of the housing 22. This valve is mounted upon a valve stem 50, and upon opposite ends of the stem are the pistons 51 and 52 fitting in cylinders 53 and 54 formed at opposite ends of the valve housing 22.

VThese cylinders are closed by heads 55 and some of the compressed air at the boosted pressure to the cylinders 53and 54 of the main valve motor. It will be noted from Fig. 4 that the pistons of the main valve motor have leakage ports 63 therethrough for the purpose of letting the`pressures upon opposite sides of the. pistoris equalize after the piston has been driven to the limit of its movement.

The inlet valves 40-40 (Fig. 4)' control, or valve, ports through the cylinder heads 34 and 35 from pipes 64 and 64', respectively, which are manifolded together at 10 and to the compressed air connection 9 and the:

pipe 9 which leads to the D valve chamber in the integral housing 22.

Air at normal pressure of from 70 to 90 pounds passes from the reservoir 4 to the v pipe 7 and connection 9, and, assuming that the valve/13 is open, air lls the ends of the cylinders 30vand 31 beyond the plungers 32 and 33. This lis because the check valves 40 open inwardly and permit the air to pass in and equalize the pressure against opposite ends of the plungers 32 and 33. At the same time, air passesthrough the manifold connection into the interior of the valve(l driven toward the top as viewed in Fig. 4,

compressing the air and drivilg the same past the check valve 41, and iin ly striking the valve stem 62 of the valve 61 in cylinder head 34, and thereby discharging a small quantity of high ressure air through the port 59 through yexible tubing connection' 57 to' the top of the motor plston 51 driving said valve motor, together .with the valve 47, to the lowermost osition. 'Pressures uickly equalize upon t e o posite sides of t e pistons 51 and 52, and t e return stroke is then made, the lower end of double-acting cylinder 20`being then connected to exhaust and the top end, above the piston 21, belng connected to live air. The booster will then proceed to dischar air at any desired pressure between the ow pressure air 1n the pipe 9 and any higher pressure which is 1n roportion to the ratios of the piston areas. 'hat is to say, the ratios of the p1ston areas determine at what boosted or terminal pressure the booster will stall and end its upper working limit. It is not necessary to pump or boost all of the air to the maximum pressure, as air at a less pressure is quite s uitablev so long as it will overcome a reslstance.

With automatic valve 16 closed, the booster will make a few strokes filling the hne and flexible pipe 15, and then w11 s tand under pressure until a1r is drawn, )ust like -a faucet controlled pneumatic displacement water pump.

and booster 12 stan s under pressure in the system indicated in Fig. 1, low pressure air may be drawn at the valve 11, or high pres-l sure air ma be drawn at the valve 16.

If desire a suitable commonA controlling valve 70, as shown in Figs. and 3, may be employed for utllizin a single hose and valve and to connect t e same to either the reservoir 4 or to the booster 12 and to connect the booster automatically to the receiver 4 where high pressure air is desired.

The valve has four connections; namely, the connection 7 from 'the receiver, the connection 71 leading to the booster corresponding to the pi e 9 of Fig. 1, the pi igh pressure mamfo d 72 leading to the of the booster, and the the common hose and va ve such as shown at 15-16 in Fig. 1. The valve 70 comprises a suitable body 74 and plug 75, preferably ipe 73 leading to fitted on a t'r as is common in valves of this class. 's valve plu has a suitable handle 76 and a pointer 7 playing over a suitable indicating dial 78 for "indicating when the hose is connected to high pressure orlow pressure. The valve plug has an .axlal passageway 79 communicating at all times with the receiver connection 7 and having a radial port 80 which is adapted to -be brought into register or out of register is connected-to the booster for supplying' air thereto.

It will be noticed in theoperation of the booster that each vcylinder full of air is supplied to the connection 9, and hence the cyl-l inder is filled completely with air for each stroke. Hence there is a maximumv effectiveness of the booster and evenness of load which permits the device to operate etlicientlly and at relatively high speed. Even when the demand. for high pressure air is great, there is suiicient trapping of air, by the restriction ofthe discharge passagev'vays, to prevent pounding of the piston against the cylinder heads. Y

As above stated, the booster may be made to operate inltwo stages by reducing the diameter of one compressor cylinder and causing the other cylinder to discharge dir rectly into said smaller cylinder by a connection such as shown in the manifold I3-44. The reduction in diameter-of the Therefore, so lon as the valve 13 1s open second stage compressor cylinder and piston does not disturb the. balanced relation since the sum of the pressures acting in the particular direction to make a stroke remains the same; that is to say, assume that the cylinder 30 and its piston are reduced in diameter, then`the total area-is less, and' even if a' higher unit pressure is encoun tributing the air from said booster at a high/ pressure, said booster operable only upon demand for high pressure. air.

2. A system of the class described coinrisinga single stage compressor, a receiving tank therefor for storing .air at a relatively low ressure, automatic means for starting an stopping the compressor to maintain a given pressure in said tank, means for distributing air at said low pressure, an air operated booster connected to said tank for taking air from said tank and delivering it at a relatively high pressure, and means for distributing sai high pressure air, said booster operable only upon demand for high pressure air.

3. Incombination, a receiver, a compressor for charging said receiver with compressed air to a relatively low dpressure, a booster operated by compresse air from said receiver to discharge air at a relatively high pressure, and a distributing hose having a normally closed, manually controllable outlet connected to the delivery side of said booster, said booster being adapted to be stalled by back pressure when the outlet is closed.

4. In combination, a receiver, a compressor for automatically charging the receiver to a relatively low pressure, a booster operated by compressed air from said receiver tov compress a part of the air taken from the receiver to a relatively high pressure, a

distributing hose, and a valve for connecting s aid hose at Will to the delivery side of the booster or to the receiver.

5. In combination, a receiver, a compressor for automatically charging-the receiver to a relatively low pressure, a booster operated bycompressed air from said receiver to compress a part of the air taken from the receiver to a. relatively high pressure, a

distributing hose, and a valve for connecting the booster to the tank and the hose to the booster, or to disconnect the booster from the tank and connect the hose directly to said tank.

6. In combination, a receiver, a compressor for A automatically charging the receiver to a relatively low pressure, a booster hav-` ing an intake connection and a discharge connection and constituting means for automatically taking air from the receiver and.

compressing a part thereof to a relatively high pressure, a distributing hose, a valveA having a tank connection, a hose connection, a booster intake connection and a booster delivery connection, said valve having a movable elementr for establi'shin simulta-l neous communication of the tan connection with booster intake and of the booster delivery with the hose.

7. In combination, a' receiver, a compressor for automatically charging the receiver toa relatively low pressure, a booster having an intake connection and a discharge connection and constituting .matically taking air from the receiver and compressing a part thereof to a relatively high pressure, a distributingy hose, a valve having a tank connection, a hose connection, a booster intakeconnection and a booster delive connection, said valve having a movab e element for establishing simultaneous communication of the tank connection with booster intake and of the booster delivery with the hose, said movable element 9. In combination, a receiver, a first means for charging the said receiver with 100 a medium under pressure, a secondmeans operated by the medium under pressure from said receiver for increasing the pressure of the said medium, anda third means having a normally closed outlet connected 10.5

to the s aid second means for distributing the medium under pressure, thelsaid second means being adapted to be stopped by back pressure when the said outlet is closed.

10. In lcombination, a receiver, a first 110 means for charging the said receiver with a medium under pressure, a second means operated by the said medium under pressure for increasing the pressureof thesaid metank connection and the` means for autodium under pressure, a distributing element,

and a member connecting the second means to the receiver and the element to the vsecond means, or to disconnect the second means `from the receiver and connect the ele-A ment directly to the said receiver.

l1. In combination, a receiver, a irst means for charging the said receiver with a medium under pressure, and a second means operated by the medium under pressure from said receiver for increasin the 'pressure of the said medium comprising three connected pistons one of which is of a greater effective diameter than the others, three cylinders therefor, the cylinders of the small pistons having automatic intake check i valves adapted to be connected t`o the medium under pressure and vhaving' automatic discharge check valves connected to a common discharge outlet, and an automatic control valve for the said one cylinder, a motor for the control valve and a pilot valve actuated upon the completion of a stroke for admitting medium under pressure to the said motor to shift the valve.

12. In combination, a receiver, a first means for charging the said receiverA with a medium under pressure, and a second means operated by the medium under pressure from said receiver for increasing the 'pressure of the said medium, comprising a central motor cylinder of relatively large diameter, a double acting piston therein, compressor cylinders at the ends of the motor cylinder, single acting pistons in said compressor cylinders connected to said compressor cylinders, said cylinders being connected to the medium under pressure, au-

tomatic intake and discharge check valves for said compressor. cylinders, a control valve for the motor piston, motor means for shifting the control valve and pilotvvalve means operated upon the end of the strokes of the 'pistons for controlling the operation .of said motor means.

13. In combination, means for putting a medium under pressure, and means operable by the said medium under pressure for. increasing the pressure of the said medium comprisin a central motor cylinder, a double actin piston therein, compressor cylinders of re atively smaller diameter connected to the ends of said motor cylinder, single acting compressor pistons connected to said motor piston, the said cylinders being connected to the said medium under pressure, a discharge connection for said compressor cylinders for delivering high pressure medium, a motor control valve, a valve motor therefor and means for admitting high pressure medium to the valve motor upon the completion of the compression stroke.

14. In combination, a receiver, means for charging the said receiver with a medium connected to said motor piston, the said cylinders being connected to the said medium under pressure, a discharge connection for said compressor cylinders for delivering high pressure medium, a D-slide valve for the motor cylinder, an opposed piston motor for shifting said slide valve, and pilot valves for said compressor cylinders for controlling the shifting of said opposed piston motor.

15. In combination, means for putting air under pressure, and means operable by the said air under pressure for increasing the pressure of the said air comprising a central motor cylinder, a double acting piston therein, compressor cylinders of relatively smaller diameter -connected to the ends of said motor cylinder, single acting compressor pistons connected to said motor piston, means for supplying compressed air to all of said cylinders, a discharge connection for said compressor cylindery delivering high pressure air, a control valve for controlling the strokes of the motor piston, and pneumatic means actuated at the end of each compression stroke to shift said control valve.

16. In combination, a first means for putting a medium under pressure, a receiver for said medium under pressure, a second means operable by said medium under ressure for increasing the pressure of said medium under pressure, a third means for selectively dispensing the said medium under pressure from the said receiver and the medium under high pressure from the -said second means, said second means being operable only upon demand for said medium under high pressure.

In witness whereof, I hereunto subscribe my name this 28th da of February, 1924.

BUR ON S. AIKMAN. 

